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AJvYcCUm6xLw0Q7dXb4k+HY8xSOhiCWhEmqdbgTLf1xn+pwgPxRJGBbnUB+iyV4ygIJKjNdqPYzC0e9lwQ==@kvack.org X-Gm-Message-State: AOJu0YzbDJ4YzufGe6sls2b5bvZclKbxhque0X6b1IBJPfYGUZTfyeZs ptO/rumurf+1royuNQOk5rmSREKi345tAZOa57EEA9gMRAdlo53fds36OdF3zjDpQI6JWk3SRbr n8A== X-Google-Smtp-Source: AGHT+IGBogaOn/a2nRCbQgtEGBqaMIjNeCnMyNgJrpcQg8cMebuy76dboaZmnJsfg8PNbJXBbdCUps7GZQ== X-Received: from wmbes26.prod.google.com ([2002:a05:600c:811a:b0:456:217f:2625]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:34c5:b0:43c:fe5e:f040 with SMTP id 5b1f17b1804b1-45565edc8f4mr129943955e9.23.1752572067858; Tue, 15 Jul 2025 02:34:27 -0700 (PDT) Date: Tue, 15 Jul 2025 10:33:46 +0100 In-Reply-To: <20250715093350.2584932-1-tabba@google.com> Mime-Version: 1.0 References: <20250715093350.2584932-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250715093350.2584932-18-tabba@google.com> Subject: [PATCH v14 17/21] KVM: arm64: nv: Handle VNCR_EL2-triggered faults backed by guest_memfd From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com, tabba@google.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A6D764000D X-Stat-Signature: q4uijjhbb3zzhhedi8pc661ksys6wg7h X-Rspam-User: X-HE-Tag: 1752572515-471866 X-HE-Meta: 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 +jjfbCxy 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Handle faults for memslots backed by guest_memfd in arm64 nested virtualization triggerred by VNCR_EL2. * Introduce is_gmem output parameter to kvm_translate_vncr(), indicating whether the faulted memory slot is backed by guest_memfd. * Dispatch faults backed by guest_memfd to kvm_gmem_get_pfn(). * Update kvm_handle_vncr_abort() to handle potential guest_memfd errors. Some of the guest_memfd errors need to be handled by userspace, instead of attempting to (implicitly) retry by returning to the guest. Suggested-by: Marc Zyngier Signed-off-by: Fuad Tabba --- arch/arm64/kvm/nested.c | 41 +++++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index dc1d26559bfa..b3edd7f7c8cd 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1172,8 +1172,9 @@ static u64 read_vncr_el2(struct kvm_vcpu *vcpu) return (u64)sign_extend64(__vcpu_sys_reg(vcpu, VNCR_EL2), 48); } -static int kvm_translate_vncr(struct kvm_vcpu *vcpu) +static int kvm_translate_vncr(struct kvm_vcpu *vcpu, bool *is_gmem) { + struct kvm_memory_slot *memslot; bool write_fault, writable; unsigned long mmu_seq; struct vncr_tlb *vt; @@ -1216,10 +1217,25 @@ static int kvm_translate_vncr(struct kvm_vcpu *vcpu) smp_rmb(); gfn = vt->wr.pa >> PAGE_SHIFT; - pfn = kvm_faultin_pfn(vcpu, gfn, write_fault, &writable, &page); - if (is_error_noslot_pfn(pfn) || (write_fault && !writable)) + memslot = gfn_to_memslot(vcpu->kvm, gfn); + if (!memslot) return -EFAULT; + *is_gmem = kvm_slot_has_gmem(memslot); + if (!*is_gmem) { + pfn = __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0, + &writable, &page); + if (is_error_noslot_pfn(pfn) || (write_fault && !writable)) + return -EFAULT; + } else { + ret = kvm_gmem_get_pfn(vcpu->kvm, memslot, gfn, &pfn, &page, NULL); + if (ret) { + kvm_prepare_memory_fault_exit(vcpu, vt->wr.pa, PAGE_SIZE, + write_fault, false, false); + return ret; + } + } + scoped_guard(write_lock, &vcpu->kvm->mmu_lock) { if (mmu_invalidate_retry(vcpu->kvm, mmu_seq)) return -EAGAIN; @@ -1292,23 +1308,36 @@ int kvm_handle_vncr_abort(struct kvm_vcpu *vcpu) if (esr_fsc_is_permission_fault(esr)) { inject_vncr_perm(vcpu); } else if (esr_fsc_is_translation_fault(esr)) { - bool valid; + bool valid, is_gmem = false; int ret; scoped_guard(read_lock, &vcpu->kvm->mmu_lock) valid = kvm_vncr_tlb_lookup(vcpu); if (!valid) - ret = kvm_translate_vncr(vcpu); + ret = kvm_translate_vncr(vcpu, &is_gmem); else ret = -EPERM; switch (ret) { case -EAGAIN: - case -ENOMEM: /* Let's try again... */ break; + case -ENOMEM: + /* + * For guest_memfd, this indicates that it failed to + * create a folio to back the memory. Inform userspace. + */ + if (is_gmem) + return 0; + /* Otherwise, let's try again... */ + break; case -EFAULT: + case -EIO: + case -EHWPOISON: + if (is_gmem) + return 0; + fallthrough; case -EINVAL: case -ENOENT: case -EACCES: -- 2.50.0.727.gbf7dc18ff4-goog